This code indicates that the motor rotation is influenced by reading data in a text file.
90
180
260
80
Those don't look like floats to me. So, why are you calling parseFloat()?
please kindly help me to construct the code.
What is the problem? You need to remember the old value and subtract the new value from the old value to get the delta. Then, set old value to new value.
Or, store nothing but delta values in the file.